Cable and carriage drive for grapple yarder

ABSTRACT

A grapple yarder is described having an engine-driven cablereeling structure including a plurality of drums with gear drives and clutches for engaging the drive mechanism with the respective drums. The drum system includes an outhaul drum which carries the outhaul cable normally used as a running skyline whereby it both supports the grapple carriage and pulls it outwardly from the yarder; and a pair of main line drums for reeling a two-part inhaul line to move the carriage inwardly with associated drive gear, clutches and brakes such that each drum may be operated or stopped independently and a differential mechanism positioned between the main drums effective to drive them simultaneously but in opposite directions, as may be required to operate a load line or tag line attached to one part of the inhaul line.

United States Patent [191 Cheldelin et al.

[451 Jan. 15, 1974 1 CABLE AND CARRIAGE DRIVE FOR GRAPPLE YARDER [73] Assignee: I Skagit Corporation, Sedro Woolley,

Wash.

[221 Filed: Feb. 23, 1972 [21] Appl. No.: 228,679

France 254/185 France 254/185 Primary Exari1inerRichard A. Schacher AttorileyRobert C. Smith et al.

[57] ABSTRACT A grapple yarder is described having an engine-driven cable-reeling structure including a plurality of drums with gear drives and clutches for engaging the drive mechanism with the respective drums. The drum system includes an outhaul drum which carries the outhaul cable normally used as a running skyline whereby it both supports the grapple carriage and pulls it\outwardly from the yarder; and a pair of main line drums for reeling a two-part inhaul line to move the carriage inwardly with associated drive gear, clutches and brakes such that each drum may be operated or stopped independently and a differential mechanism positioned between the main drums effective to drive them simultaneously but in opposite directions, as may be required to operate a load line or tag line attached to one part of the inhaul line.

6 Claims, 4 Drawing Figures PAIENIEU JAN 1 5 I974 sum 1 or 2 CABLE AND'CARRIAGE DRIVE FOR GRAPPLE YARDER BACKGROUND .OF THE INVENTION Yarding machines or yarders have been used in the logging industry for many years to provide a means for transporting felled logs from the field or yard where felled to a location adjacent a logging road where they may be loaded onto a truck and transported to a sawmill. A yarder is typically a very large vehicle, often of track-laying type, which includes an engine, a boom and mast structure with a plurality of sheaves, and engine-driven cable-carrying drums which operate to transport the cable and a load-carrying carriage across a portion of the yard. In setting up the yarder, cable is typically suspended to form a running skyline" from the yarder outwardly across the yard to a tail block which may be a spar tree to which is attached a sheave or tail block, and from thence to the back side of a carriage assembly which rides on the sky line. Pulling in on such a sky line will cause the carriage to be moved outwardly from the yarder. Cables are also connected from the carriage assembly back to the yarder to control the movement of the carriage toward the yarder and, sometimes, also to control lifting of the load.

A series of drums is used for controlling operation of the cable including, as a minimum, a haulback drum, around which is carried the running sky line, and a split or two-part main line drum, the separate parts of which are sometimes referred to as the holding drum and the closing drum. In controlling the operation of the drums to feed the cable as desired, the operators of yarders now generally in use will operate a series of clutches and brakes to hold some drums and drive others or release the brakes and engage the clutches to drive all drums, etc. Thus, to cause the carriage to move outwardly from the yarder, brakes are released and clutches engaged to wind the cable onto the haulback drum, while the main line drums are caused to reel out cable. To move the carriage inwardly, the main line drums are each reeled in andthe cable is reeled off the haulback drum.

For grapple yarding it is customary to connect a line to one part of the main line or inhaul line with its opposite end connected to the trip mechanism of the grapple to cause the grapple to either open from closed position or close from an open position. This tripping is normally accomplished by either feeding one part of the main line outwardly and the other part inwardly while holding the haulback (sky line) stationary, or by braking the haulback and one part of the main line and moving the other a short distance. The same reverse operation of the main drums may be used for choker yarding, but with substantially longer travel of the load line which may be attached to the main line and driven through the carriage to reach the log it is desired to move. When the choker line has been attached to the load, the sky line (outhaul) isbraked, and the main line drum clutches are reversed to cause the load to move toward the carriage while holding the carriage stationary. When the load is as near the carriage as desired, the drive to the drums is stopped and the clutches are then engaged to cause the carriage to move toward the yarder, as described.

The operation described above, while effective, has disadvantages in that the use of brakes and slipping clutches to control the operation of the drums gives rise to inefficiency and, in some operations, an excessive generation of heat with rapid deterioration of brake linings and other parts. This problem is compounded by the slipping required of some of the clutches to accommodate the speed differences resulting from the varying effective diamters of the reels as several layers of cable are reeled off and on. Also, the operation tends to require quite a high level of coordination of the operator, since he frequently must simultaneously engage a clutch and carefully feather" a brake control to maintain tension in a cable being reeled out as another is reeled in.

SUMMARY Applicants cable and carriage drive system provides for smoother and simpler operation of the clutches and brake mechanisms through the arrangement described below in which, among other things, a differential drive mechanism is incorporated between two parts of a split main drum arrangement, thus providing a capability of smoothly driving the two drum sections at equal speeds and opposite directions. With this arrangement the operator is not required to provide the carefully coordinated feathering" of a brake as the opposite clutch is engaged as described above. This arrangement is incorporated into a drum drive system wherein the drums are also dimensioned to minimize the drum speed differentials experienced as cable is reeled from a full drum to a nearly empty drum. As compared with existing equipment, these speed differentials have been reduced to approximately one-third of that typical of earlier designs, thus substantially reducing the heat generated in the clutches and making for more efficient and smoother operation and reduced operator fatigue.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of a grapple yarder showing a typical cable and carriage arrangement for yarding logs;

FIG. 2 is a plan view, partially schematic, showing the cable drum drive arrangement according to our invention;

FIG. 3 is a view, partially in section, of the two-part main drum assembly and drive structure of FIG. 2; and

FIG. 4 is an enlarged view of a portion of FIG. 3 showing greater detail of the differential drum drive mechanism.

DESCRIPTION OF THE PREFERRRD EMBODIMENT The yarding system shown generally in FIG. 1 comprises a grapple rigged between inhaul and outhaul lines which extend from cable-winding drums mounted on a yarder 10. In this system, a haulback line 11 is shown extending from a haulback cable winding drum 12 through a fairlead assembly mounted atopa tower or boom 14, through a stump-mounted tail block 16, to the back side of a suspension carriage l8. The carriagesupporting sheaves ride on the part of the haulback line that extends between the fairlead assembly and the tail block. The two-part main line, consisting of parts 20a and 20b, extends from one main line cable-winding drum and a tower-mounted sheave, around a sheave positioned at the head end of the carriage l6, and back through another tower-mounted sheave to another main line cable-winding drum. A grapple 22 is fixedly suspended from the under side of the carriage, and a tag line 24 extends from the grapple as the grappleoperating or control line, around a sheave mounted on the carriage, and is connected to one part of the twopart main line at 26. This describes a typical carriage drive arrangement for which our invention is particularly advantageous, but is is also applicable to many other arrangements.

FIG. 2 is a plan view, in schematic form, showing the cable drum drive mechanism incorporated into the yarder of FIG. 1. A prime mover 28 drives through a transmission 30 into a main drive shaft 32 which supplies power both to the driving wheels or tracks and through a bevel gear arrangement 34 and additional gears 36 to a drive shaft 38 which turns drum drive gears 40, 42. Gear 40 engages a drive gear 44 which operates through a drive clutch 46 to drive a haulback drum 12. Band brakes 48 and 59 operate simultaneously as required to restrain rotation of the haulback drum 12. At the opposite end of haulback drum 12 is an interlock gear 52 and an interlock clutch 54.

Similarly, gear 42 engages a drive gear 56 through a drive clutch 58 to rotate the shaft 59 upon which are carried a first main drum 60, called the closing drum, and a second main drum 62, also called the holding drum. Drum clutches 64 and 66 control the engagement of the closing drum and holding drums, respectively, and band brakes 68 and 70 may be independently engaged to hold the closing drum or the holding drum respectively. Positioned between the closing drum 60 and holding drum 62 is a drum reverser mechanism 72 which provides a differential drive for the closing and holding drums and which is discussed further below. Also mounted on shaft 59 is an interlock drive gear 74 which is engageable with drive gear 40 and which may be engaged with shaft 59 through the action of an interlock clutch 76, also discussed below. Additional drive shaft, gear and clutch mechanisms are shown for operating a straw drum 75 and topping and guy line drums 77, 79 which are included in the yarder but which are not a part of the present invention.

FIG. 3 is a view, partially in section, showing somewhat more detail in connection with the holding and closing drum assembly. The transversely mounted shaft 59 is supported in suitable bearings on a pair of members 80 and 82 forming part of the frame structure of yarder 10. The drive gear 56 is connected with the shaft 59 through a drive clutch 58, keyed to the shaft by means of a key 61. The closing drum 60 and holding drum 62 are connected with the shaft 59 through clutches 64 and 66, respectively. In this view, the band brakes 68 and 70 for drums 60 and 62 are not shown. The interlock drive gear 74 is connected through the interlock clutch 76 to the shaft 59. It will be observed that clutches 66 and 76 are shown fastened to the shaft by means of keys 86 and 88, respectively, and clutch 64 is similarly keyed to the shaft. It will be observed that suitable bearings and spacers are shown for supporting drum 62 and gear 74 with respect to the shaft 59, and gears 56 and drum 62 are similarly supported.

Located adjacent the inner flange ,of each of drums 60 and 62 is a ring gear, such as gear 90 carried on flange 92. A pinion 94 is shown meshed with ring gear 90, and this pinion is also engaged with a similar ring gear 96, partially shown in FIG. 4, which is attached to a flange 98 of drum 60. Pinion 94 is supported in suitable bearings 100, 102 and is mounted for free rotation with respect to a supporting wheel member 104 which carries pinion 94 and a plurality of other pinion members similarly fastened thereto. A brake band 106 is operable to restrain rotation of flanged wheel 104 and the corresponding pinion members.

With the structure thus far described, it is apparent that the operator has a number of options with respect to control of drums 60 and 62. With drive gear 56 engaged to the shaft 59 through clutch 58, the operator may hold drum 62 by means of brake and engage clutch 64 to drive drum 60 as desired. Alternatively, he may hold closing drum 60 by means of bank brake 68 and by operating clutch 66 drive the holding drum 62. He may also engage each of clutches 64 and 66 along with brake 106 which operates to restrain the ring member 104 and the respective pinions, thereby causing drums 60 and 62 to rotate at equal rates but in opposite directions.

Referring to FIG. 2, operation will perhaps be more easily understood if the reader is aware that the interlock gears operate to drive cable off of their respective drums and the drive gears are engaged to pull cable onto the drums. Thus, when it is desired to pull the carriage 18 toward the.yarder 10, the main gear 56 is engaged with the shaft 59 through clutch 58, and clutches 64 and 66 are engaged to wind cable onto drums 60 and 62 simultaneously. At the same time, the interlock gear 52 and interlock clutch 54 operate to reel cable 11 off of the haulback drum 12. The gear ratios are chosen such that cable is effectively pulled from the haulback drum 12 faster than the drum is driven, thereby maintaining a desired amount of tension in the haulback cable 11. With this arrangment it is apparent that the interlock clutch must slip somewhat, and the clutch typically includes means for controlling the amount of tension maintained in the cable being pulled from the haulback drum 12. When the cable has reached the desired location adjacent the yarder 10, the drive of drums 60 and 62 is terminated, and these drums are held by means of the brakes 68 and 70 while some additional cable is slipped from the haulback drum 12 to cause the entire carriage assembly 18 to sag toward the landing adjacent the yarder.

The grapple 22 itself may be any of several types, such as a power-closed type, power-open type, singleline cycling type, etc. If a power-open grapple is employed wherein pulling the tag line 24 opens the grapple, the operator would then operate the main drum differential drive mechansim as described to wind in a short distance on line 200 while at the same time winding outwardly on line 20b, thereby causing the grapple 22 to open, releasing the log.

To cause the carriage 18 to move outwardly toward tail block 16, the haulback drive gear 44 and drive clutch 46 are engaged to reel in on haulback line 11, thereby causing the carriage 18 to move away from the yarder. At the same time, interlock drive gear 74 and interlock clutch 76 are engaged to drive cable from drums 60 and 62 equally. Again, because of the ratios chosen, the operation of the haulback drum drive will tend to pull cable from the drums 60 and 62 at a rate somewhat faster than these cables are driven through the interlock drive, thereby requiring some slipping of the interlock clutch 76. This maintains adequate tension in the lines to hold the carriage in suspension. This drive then proceeds until the carriage reaches the area of the felled log which it is desired to move, and the main drums 60 and 62 are then held, and slack is fed into line 11 from the haulback drum to permitthe carriage 18 to sag down to thelocation of the log, placing the grapple over the log. The operator then reverses the main line differential drive, when causes the grapple to close around the log, and the log is then lifted preparatory to being moved toward the landing as described.

One particular problem which has been encountered is in the amount of slip required to be dealt with as the cable is reeled from the drums and, therefore, the capability of the interlock clutches to withstand the slip. It is not unusual for the depth of cable wound on the drums to be sufficiently great that the resulting speed differential between the drums, as the cable is unwound from a full drum to an almost empty drum, gets close to 80 percent, which requires that a substantial amount of energy be asborbed by the clutches. Applicants have provided quite large drums which permit limiting the depth of cable wound thereon such that this speed differential does not exceed about 25 percent, which has been found well within the capability of the interlock clutches.

For choker operation, the tag line 24 would be replaced with a substantially longer load linewhich is attached to one of the two inhaul lines 20a or 20b in a manner similar to the attachment 26. With this type of operation, it is frequently desired to carry the load line a substantial distance away from the carriage l8 (laterally to the sky line), and this is accomplished through the previously described differential operation of the closing drum 20 and holding drum 62 such that the carriage 18 is maintained at a given distance from the yarder while the load line is reeledoutwardly for attachment to a turn of logs held by a choker cable, and the choker crew will then attach the choker cable to the load line. A reversing of this differential drive arrangemcnt will cause the load line to be reeled in, carrying the attachment 26 toward the yarder l0, and the log is carried to a desired position near the carriage 18. Transporting of the log toward the landing adjacent the carriage is then effected in the manner described above.

While the operation of applicants cable and carriage drive has been described in connection with a particular carriage arrangement, which is typical, those skilled in the art will recognize that alternate cable arrangements commonly used with special terrain situations are well within the capabilities of applicants drive mechanism.

We claim:

1. In a yarder for operating a system of cables and a carriage running on said system for transporting of logs, said yarder having a frame, and an engine mounted on the frame, a cable and carriage drive system comprising a plurality of shafts supported on said frame, a plurality of drums on said shafts for storing and feeding said cables including at least first cable means, a haulback drum for controlling said first cable means to provide a running sky line for supporting said carriage and operative to move said carriage away from said yarder, second cable means, and a pair of main drums carried on one of said shaft for controlling said second cable means,

a plurality of engine-driven gears positioned on said shafts,

control means for said main drums comprising a drive clutch associated with one of said gears operative to engage the main drum shaft,

first and second drum clutches associated with said main drums to selectively engage one or both of said drums with said main drum shaft and first and second brake mechanisms associated with said main drums,

a drum reverser mechanism including a ring gear fastened to each of said main drums, a pinion positioned between and meshed with said ring gears, and brake means effective, when engaged, to hold said pinion and cause rotation of said main drums at equal speeds and opposite directions,

a drive clutch positioned on said haulback drum shaft and associated with one of said gears,

brake means operable to stop rotation of said haulback drum,

and interlock gear and clutch means operably connected to the shafts of said main and haulback drums, the ratios of said gears being chosen such that when cable is reeled onto one of said haulback and main drums to move said carriage, cable is reeled off from the other of said drums at a rate somewhat faster than would occur from the interlock gear drive rotation alone, thus slipping said interlock clutch means.

2. A cable and carriage drive system for a yarder as set forth in claim 1 wherein the dimensions of the drums and the depth of cable carried thereon have been chosen to limit the speed difference between full and empty drums resulting in slipping of the interlock clutch means to a maximum of approximately 25 percent.

3. A cable and carriage drive system for a grapple yarder having a frame and prime mover means, said system comprising first and second shafts supported on said frame,

a first drum mounted on a first of said shafts and second and third drums mounted on a second of said shafts,

a plurality of gears mounted on said shafts common to said drums and means providing connections from said prime mover means to said gears,

a drive clutch mounted on said first shaft for connecting said first drum to a gear to rotate said drum in a direction to wind on cable,

an interlock'clutch on said first shaft for connecting said first drum to a gear to drive said drum in a direction to reel off cable,

brake means for restraining rotation of said first drum.

a drive clutch mounted on said second shaft for conecting said shaft to one of said gears to drive said shaft in a first direction and an interlock clutch mounted on said second shaft for connecting said shaft to one of said gears to drive said shaft in a second direction,

a first drum clutch mounted on said second shaft for connecting said second drum to be driven by said second shaft,

a second drum clutch mounted on said second shaft for connecting said third drum to be driven by said second shaft,

brake means for restraining rotation of said second and third drums,

and a drum reverser mechanism including a ring gear fastened to each of said second and third drums, a

forth in claim 4 wherein the dimensions of the drums and the depth of cable reeled thereon are such as to limit the reel speed difference between full and empty reels to approximately 25 percent.

6. A cable and carriage system for a yarder as set forth in claim 3 wherein said drum reverser mechanism includes a flanged wheel carried on said second shaft, a plurality of pinions are carried on said wheel and meshed with said ring gears, and said brake means operates to restrain said wheel from rotation.

l l= l 

1. In a yarder for operating a system of cables and a carriage running on said system for transporting of logs, said yarder having a frame, and an engine mounted on the frame, a cable and carriage drive system comprising a plurality of shafts supported on said frame, a plurality of drums on said shafts for storing and feeding said cables including at least first cable means, a haulback drum for controlling said first cable means to provide a running sky line for supporting said carriage and operative to move said carriage away from said yarder, second cable means, and a pair of main drums carried on one of said shafts for controlling said second cable means, a plurality of engine-driven gears positioned on said shafts, control means for said main drums comprising a drive clutch associated with one of said gears operative to engage the main drum shaft, first and second drum clutches associated with said main drums to selectively engage one or both of said drums with said main drum shaft and first and second brake mechanisms associated with said main drums, a drum reverser mechanism including a ring gear fastened to each of said main drums, a pinion positioned between and meshed with said ring gears, and brake means effective, when engaged, to hold said pinion and cause rotation of said main drums at equal speeds and opposite directions, a drive clutch positioned on said haulback drum shaft and associated with one of said gears, brake means operable to stop rotation of said haulback drum, and interlock gear and clutch means operably connected to the shafts of said main and haulback drums, the ratios of said gears being chosen such that when cable is reeled onto one of said haulback and main drums to move said carriage, cable is reeled off from the other of said drums at a rate somewhat faster than would occur from the interlock gear drive rotation alone, thus slipping said interlock clutch means.
 2. A cable and carriage drive system for a yarder as set forth in claim 1 wherein the dimensions of the drums and the depth of cable carried thereon have been chosen to limit the speed difference between full and empty drums resulting in slipping of the interlock clutch means to a maximum of approximately 25 percent.
 3. A cable and carriage drive system for a grapple yarder having a frame and prime mover means, said system comprising first and second shafts supported on said frame, a first drum mounTed on a first of said shafts and second and third drums mounted on a second of said shafts, a plurality of gears mounted on said shafts common to said drums and means providing connections from said prime mover means to said gears, a drive clutch mounted on said first shaft for connecting said first drum to a gear to rotate said drum in a direction to wind on cable, an interlock clutch on said first shaft for connecting said first drum to a gear to drive said drum in a direction to reel off cable, brake means for restraining rotation of said first drum, a drive clutch mounted on said second shaft for connecting said shaft to one of said gears to drive said shaft in a first direction and an interlock clutch mounted on said second shaft for connecting said shaft to one of said gears to drive said shaft in a second direction, a first drum clutch mounted on said second shaft for connecting said second drum to be driven by said second shaft, a second drum clutch mounted on said second shaft for connecting said third drum to be driven by said second shaft, brake means for restraining rotation of said second and third drums, and a drum reverser mechanism including a ring gear fastened to each of said second and third drums, a pinion positioned between and meshed with said ring gears, and brake means effective to hold said pinion in place and cause simultaneous rotation of said second and third drums in opposite directions.
 4. A cable and carriage drive system for a yarder as set forth in claim 3 wherein the ratios of said gears are chosen such that said drive gears drive their corresponding drums to reel cable in at a slightly faster rate than the interlock gears drive cable off, thereby slipping said interlock clutches.
 5. A cable and carriage system for a yarder as set forth in claim 4 wherein the dimensions of the drums and the depth of cable reeled thereon are such as to limit the reel speed difference between full and empty reels to approximately 25 percent.
 6. A cable and carriage system for a yarder as set forth in claim 3 wherein said drum reverser mechanism includes a flanged wheel carried on said second shaft, a plurality of pinions are carried on said wheel and meshed with said ring gears, and said brake means operates to restrain said wheel from rotation. 